1. Field of the Invention
The present invention relates to an electrically controlled configuring device having a tip section provided at a distal end of a wire arrangement and a regulation unit provided at a proximal end of the wire arrangement, the device being adapted to be inserted into an interior channel within an elongated flexible component to stiffen that component and bend a distal end section thereof into a required shape.
An elongated flexible component of the aforementioned kind may be e.g. a hollow electrode cable used for stimulation in the human body, e.g. an electrode cable or pacing lead for a heart stimulator. Such electrode cable may be devised to serve either as an implant or for removal from the human body after a medical treatment has been performed.
2. Description of the Prior Art
A standard type of body insert configuring device generally in use today is a stylet unit (or mandrin) used for stiffening and guiding an electrode cable (pacing lead) for a heart stimulator or pacemaker during insertion, advancing and positioning of such a cable or lead into a human heart, and when the contact electrode at or near the distal tip end of the cable is to be anchored in a cavity of the heart. Such a temporarily introduced stylet unit inside the electrode cable or pacing lead extends through the cable's interior channel from the proximal end of the cable to the distal end thereof where the contact electrode is mounted.
This kind of stylet unit normally has a flexible, tubular stylet shell containing a stylet wire longitudinally movable within the shell's interior channel.
To prevent the stylet wire from rotating in relation to its surrounding tubular stylet shell (sleeve) it is preferred to use a shell (sleeve) with an interior channel having a non-circular cross-section in combination with a stylet wire having a corresponding non-circular cross-section. European Application 0 773 037 A2 describes a guide wire unit where the stylet wire is prevented from rotating in its surrounding shell (sleeve) by means of interacting non-circular cross-sections.
When a pacing lead contact electrode is to be positioned and anchored in the heart's atrium using a stylet unit, it is required that an appropriate J-shape be imparted to the distal end or tip section of the pacing lead, by means of the stylet unit. A suitable J-shape will highly facilitate the insertion of the distal end section of the pacing lead into the atrial auricle as well as the anchoring of the contact electrode in the trabeculae of the atrial auricle.
After the pacing lead contact electrode has become duly positioned and anchored at the desired site in the heart, the stylet unit is withdrawn completely from the interior channel of the pacing lead and thereby from the heart.
The above kind of stylet unit is relatively difficult to manufacture and furthermore is dependent on free longitudinal movement between the two parts and it would be desirable to have a configuring device that is not dependent on relative longitudinal movement between different parts.
U.S. Pat. No. 4,758,222 discloses a device having an electrically controlled catheter. The catheter incorporates parts made of memory metal that will change from one state to another when subjected to heating. The memory metal parts are heated by means of electrical current supplied from a power unit via longitudinal conducting means. When the memory metal parts are heated, the catheter will be deflected.
U.S. Pat. No. 5,211,183 discloses a guidewire for access to a body structure or location by inserting it into the body and advancing it to the desired location. The guide wire includes shape memory means that may be heated by means of induction heating, immersion heating, application of RF energy or by body heating, the guide wire thus being deflected when heated.
Neither of the two above devices is designed for use in an internal lumen in for instance an endocardial pacing electrode lead or the like. Both also are limited to discrete changes in shape in view of the nature of shape-memory materials.